This invention relates to a process for hydrolyzing and hydrogenating cyclic acetal-aldehyde compounds in one step.
U.S. Pat. No. 2,808,440 discloses the hydrolysis in the presence of an acidic ion-exchange resin of 2,3-dihydropyran and a second step hydrogenation after removal of the acidic ion-exchange resin in the presence of a hydrogenation catalyst.
U.S. Pat. No. 2,888,492 discloses simultaneous hydrolysis and hydrogenation of acetal aldehydes in the presence of mineral acids as well as acetic acid and as a noble metal. However, in Reactions of Hydrogen with Organic Compounds over Copper, Chromium Oxide and Nickel Catalysts by Homer Adkins, p. 75, it is disclosed that acetal groups form ether linkages on hydrogenation.
As disclosed in Organic Chemistry by Fieser and Fieser, 1957, p. 157, it is also well known that aldehydes condense in the presence of acids to yield high molecular weight resinous materials. Since, chemically, the six-membered acetal ring can also be described as a masked aldehyde, it can be expected that acetal-aldehydes would polymerize in the presence of an acid to yield polymeric resinous materials. Depending on the strength of the acid, the acetal-aldehyde would be expected to condense to a greater or lesser degree, producing higher degrees of polymerization in the presence of strong acids. In addition, some important hydrogenation catalysts such as Raney nickel are attacked by acids, particularly strong acids.
U.S. Pat. No. 3,578,609 and British Pat. No. 1,236,615 disclose the preparation and use of dual function catalysts in which metals are deposited on ion-exchange resins. However, when these catalysts are applied to acetals the expected conversion of the acetal groups to ether linkages is observed.